In-vivo and in-vitro studies of the effect of specific antitoxin on the phagocytosis of cells of Clostridium botulinum type A.

Abstract

SUMMARY The conversion of heat-resistant spores of Clostridium botulinum type A into germinated heat-sensitive cells in the peritoneal cavity of mice has been observed. This in-vivo germination of spores was depressed in mice passively immunised with type-A botulinal antitoxin. Studies, in which the release of free 45Ca in the urine of mice challenged with labelled Cl. botulinum spores provided an indicator of spore germination, showed that spore germination occurred normally at 8 hr in vivo. However, the rate of germination as determined from 45Ca excretion was substantially inhibited when antibody-treated spores were used as the challenge. In in-vitro studies with guinea-pig leucocytes, spore germination was similarly assayed by monitoring the release of 45Ca from labelled spores. Spore germination in these leucocyte systems was also suppressed when the spores were first treated with Cl. botulinum type-A antitoxic serum, although phagocytic indices for antibody-treated spores and vegetative cells were increased. Release of type-A botulinal toxin was either completely prevented or substantially suppressed when Cl. botulinum spores and vegetative cells were treated with specific botulinal antibody and incubated with leucocytes. These results demonstrate that combination of spores with type-specific antibody prompted phagocytic engulfment of antibody-coated spores, but strongly inhibited subsequent phagocytic digestion of engulfed spores.